Morphogenesis and control of cell shape is being investigated in forming semicells of desmids. Morphogenesis can be temporarily interrupted by certain inhibitors of protein and RNA synthesis (e.g., cycloheximide and actinomycin-D). Radioautography with the electron microscope will now be used to follow the spatial and temporal secretion of polysaccharide and, hopefully, protein into the wall. The effects of the herbicide IPC on the ultrastructure and function of the mitotic spindle of certain algae, and also its effect on other algal cells undergoing morphogenesis, is being examined. Cell division and various aspects of morphogenesis (e.g., differentiation of zoospores, oogonia, sperm, et al.) are being studied in various algae (including Oedogonium, Bulbochaete, Pedinomonas, and Cylindrocapsa). Al observations are correlated with those on related organisms, the object being to understand how difference in these processes evolved and diversified. For example, the gross morphological differences between the closely related Oedogonium (a simple, unbranched filament) and Bulbochaete (a highly branched filament covered with differentiated, colorless hair cells) can be related specifically to the appearance in vegetative cells of the latter of a character that in Oedogonium is confined to oogonial cells: a dislocation in the structure of the cell wall that permits the formation of the fertilization pore and which in Bulbochaete leads also to the differentiation of hair cells and then the creation of branches under these hairs.